Pre-formed dental matrix band

ABSTRACT

A dental matrix band construction of the type including a central tooth-surrounding portion with arms formed at the opposite end of the tooth-surrounding portion. These arms are utilized for securing the band in position on a tooth. The central portion of the band defines a concave interior tooth engaging surface because of a bend in the upper part thereof, the concavity extending between the top and bottom edges of the central portion. The bottom edge of the band defines a straight edge while the top edge of the band is curved between the respective junctures of the arms and central portion whereby the band is progressively wider from the junctures to the mid-point of the central portion.

U ENQ States Patent Eames Oct. 22, 1974 l l PRE-FORMED DENTAL MATRIX BAND Primary Examiner-Antonio F. Guida Assistant Examiner-J. Q. Lever [76] lnvmmr' 10 Attorney, Agent, or Firm-McDougall, Hersh & Scott [22] Filed: Feb. 20, 1973 [57] ABSTRACT [21] Appl. No.: 334,004 A dental matrix band construction of the type including a central tooth-surrounding portion with arms formed at the opposite end of the tooth-surrounding portion These arms are utilized for Securing the band 5 c32/63 in position on a tooth. The central portion of the band le 0 earc defines a Concave interior tooth engaging Surface cause of a bend in the upper part thereof, the concav- [56] References C'ted ity extending between the top and bottom edges of the UNITED STATES PATENTS central portion. The bottom edge of the band defines 677,268 6/l90l Power 32/63 a straight edge while the top edge of the band is 3310443 2/1943 l- 31/63 curved between the respective junctures of the arms i t g and central portion whereby the band is progressively t H o cmire.... 1262308 7/1966 Johnson. Jr... 32/63 :23 the junctures to the pomt of the 330mm 2/1967 Tofflcmirc .t 32/63 p 5 Claims, 7 Drawing Figures PRE-FORMED DENTAL MATRIX BAND This invention relates to a dental matrix band construction. In particular, the invention is concerned with matrix bands which are utilized by locating the bands in surrounding relationship relative to a tooth whereby the band assists in retaining filling material in position during filling of a tooth cavity.

Dental matrix bands of the general type contemplated by this invention are disclosed in the prior art, for example Tofflemire U.S. Pat. No. 2,591,744. These bands are typically formed from a flexible metal strip, for example a stainless steel strip having reasonably high tensile strength and good ductility. By utilizing a suitable retainer, the bands can be secured relative to a tooth with the band surfaces conforming to the shape of the tooth. Under these conditions, a cavity which has been prepared by the dentist can be filled, and the filling material is prevented by the band from moving outwardly beyond the cavity area.

Problems develop with prior matrix bands from the standpoint of achieving proper contour of the tooth surfaces after the cavity has been filled. Thus, it is desirable to achieve natural shape for the tooth with the filling in place, and the band position during filling is not always suitable for achieving this purpose. This leads to fillings of inferior quality which may require additional work on the part of the dentist, and discomfort for the patient.

Contact of the filling material with the gingiva can lead to problems for the patient, and the matrix bands are preferably designed so that they will prevent passage of the filling material beyond the gingival border. With prior band designs, this cannot be readily achieved and, therefore, additional problems result for the dentist and patient.

It is a general object of this invention to provide an improved dental matrix band.

It is a more specific object of this invention to provide a dental matrix band which is characterized by a preformed surface contour whereby the band construction is easily adapted to the natural tooth contour of the patient.

It is a still further object of this invention to provide a matrix band design which fits around the tooth in a manner such that the passage of filling material to the gingival border can be avoided.

These and other objects of this invention will appear hereinafter and for purposes of illustration, but not of limitation, specific embodiments of the invention are shown in the accompanying drawings in which:

FIG. I is an elevational view of teeth having a matrix band of the invention encircling one tooth, the band being shown in section;

FIG. 2 is an enlarged fragmentary sectional view taken about the line 2-2 of FIG. 1;

FIG. 3 is a plan view of the arrangement shown in FIG. 1;

FIG. 4 is a perspective view of the matrix band construction;

FIG. 5 is a perspective view of the matrix band construction viewed from a different angle;

FIG. 6 is a cross-sectional view of the matrix band taken about the line 6-6 of FIG. 4; and,

FIG. 7 is a plan view of the matrix band illustrated prior to pre-forming.

The matrix band of this invention generally comprises a metallic strip defining a central tooth surrounding portion with arms formed at the ends of the central portion. The central portion is adapted to encircle a tooth while the arms are adapted for use in conjunction with a retaining means whereby the band can be held in place on the tooth.

The improvements of the invention specifically relate to the shape of the band. In particular, the central portion of the band between the junctures thereof with the holding arms are provided with a definite curvature. Considering the inner tooth engaging surface of the band, a concave curvature is presented due to a bend in an upper part of this central portion. This curvature extends completely along the central portion with the arms being formed from flat strip portions.

The bottom edge of the band which is adapted to be positioned at the gingival border is substantially straight. This straight edge is formed in the central portion as well as in the extending arm portions. The upper edge of the band comprises a straight edge in the arm portions; however, the upper edge is curved upwardly at each juncture of the arm portions with the central portion. Accordingly, the central portion of the band is progressively wider as it extends from the junctures to the midpoint of the central portion.

To achieve the configuration described, the band is initially formed from a strip blank which includes a curved bottom edge and a parallel upper edge for the arm portions. The upper edge for the central portion is curved in the manner described so that it is not in parallel relationship with the bottom edge of the central portion. In forming the band, the central portion is formed in an appropriate die, and the band is folded so that the concavity formed with the die is located on the inner tooth engaging surface between the arms. Because of the blank configuration, the folding operation results in the straight lower edge of the band.

The drawings illustrate the band construction and the association of the band with a tooth defining a cavity to be filled. FIGS. 1, 2 and 3 illustrate three teeth comprising a lower right second bicuspid l0 situated between first bicuspid l2 and first molar 14. It will be appreciated that the band is described herein in connection with these teeth; however, the matrix band itself is not limited in that respect.

The bicuspid l0 defines a cavity 16 which is packed with filling 18. As best shown in FIG. 3, the filling includes extreme lateral portions which define a curvature corresponding with the normal curvature of the tooth 10. The matrix band 20 serves as a wall which determines the curvature of the filling. It will be appreciated that if the band 20 does not assume a proper curvature, this will influence the shape of the filling. The proper curvature becomes essential for purposes of providing a filling which will be satisfactory from the standpoint of proper, dental care and which will also be suitable for the patient. In particular, the adjacent areas of the teeth 10, 12 and 14, sometimes referred to as the points of contact should be as normal as possible to achieve the desired results.

The matrix band 20 of the invention serves to provide the dentist with a highly effective instrument for obtaining a proper filling. This band as illustrated in FIGS. 4 through 7 defines a central portion 22 and oppositely directed arms 24 and 26. The band is produced from a blank as illustrated in FIG. 7. This blank is adapted to be located in a die for purposes of forming a concavity in the central portion and for folding the blank as illustrated in FIGS. 4 and 5.

The concavity of the central portion extends completely between the junctures 28 and 30 between the arms and the central portion. Accordingly, this concavity is located substantially completely around a tooth when the band is placed in position for a filling operation.

As shown in FIG. 7, the lower edge or gingival border edge 32 of the blank is curved. The upper edges 34 and 36 of the arm portions are substantially parallel with the edge 32 while the upper edge 38 of the central portion 22 is curved. This upper edge progressively extends away from the lower edge 32 from the junctures 28 and 30 so that the central portion becomes progressively wider from these junctures to the midpoint of the central portion.

When the blank is provided with the concavity and folded to the configuration illustrated, the lower edge 32 automatically becomes a straight edge along the entire length of the band. The upper edge portion 38 maintains the described relationship with the lower edge. Thus, the band in its completed form is narrowest at the junctures 28 and 30 and widest at the midpoint of the band.

The concavity is particularly formed by providing a substantially straight part 23 in about the lower twothirds of the central portion. At about the point 25, the central portion bends inwardly at an angle of between about and 30. This upper part 27 is provided with a concave curvature to facilitate fitting around the upper portion of a tooth as shown in FIG. 1.

Bands produced in accordance with the invention may come in two or more sizes. Typically, 0.002 gauge stainless steel is utilized and the widest portion of the band varies between about 6.5 and 8.0 mm.

In the use of the matrix band, conventional retaining structures can be employed. The retainer 40 illustrated in FIG. 3 defines a head 42 which includes slots for receiving the arms 24 and 26. These arms are received within a slot defined by the block 44, and a spindle 46 threaded into the block is adapted to be moved into engaging relationship with the arms. This serves to draw the matrix band tightly around the tooth. With the band configuration of the invention, the position which is assumed by the band walls is automatically determined, and this position permits the introduction of a filling which provides the desired contact points at the upper one-third of the tooth. Thus, the results desired are substantially completely achieved after the filling with a minimum of work being required of the dentist.

It has also been found that the band configuration serves to substantially completely eliminate any passage of filling material to the gingival border. The lower edge of the band can be conveniently and effectively located at the gingival border without the danger of damage to the gums and the band configuration provides an effective seal for preventing passage of the filling material below the cavity level.

lt will be understood that various changes and modifications may be made in the construction described which provide the characteristics of the invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. In a dental matrix band construction wherein the band comprises a central tooth-surrounding portion defining an inner tooth engaging surface, and arms at the opposite ends of the central portion for holding the band in position on a tooth, the improvement wherein said central portion defines a lower edge and an upper edge, said central portion being substantially straight in the lower part of the band which extends upwardly from said lower edge, and said central portion then bending inwardly in the upper part of the band whereby said tooth engaging surface is curved to define a concave configuration, said lower part extending angularly upwardly and outwardly from the lower edge of the band for about two-thirds of the height of the central portion, and said upper part bending upwardly and inwardly in the upper one-third of the central portion.

2. A construction in accordance with claim 1 wherein said band is bent along a vertical axis extending through said central portion with said arms extending on opposite sides of a vertical plane extending through said axis, the concave tooth-engaging surface comprising the interior surface of the band.

3. A construction in accordance with claim 2 wherein said concave configuration extends from the juncture of one arm with said central portion throughout the entire extent of the central portion to the juncture with the other arm.

4. A construction in accordance with claim 3 wherein said arms define a bottom edge formed as an extension of the bottom edge of said central portion, the respective bottom edges combining to form a substantially straight bottom edge, said bottom edge being positioned adjacent the gingival border when the band is in position on a tooth.

5. A construction in accordance with claim 3 wherein the upper edge of said central portion curves upwardly from one of said junctures to a midpoint of the central portion and then curves downwardly to the other of said junctures whereby said central portion is progressively wider from said junctures to the mid-point of the band. 

1. In a dental matrix band construction wherein the band comprises a central tooth-surrounding portion defining an inner tooth engaging surface, and arms at the opposite ends of the central portion for holding the band in position on a tooth, the improvement wherein said central portion defines a lower edge and an upper edge, said central portion being substantially straight in the lower part of the band which extends upwardly from said lower edge, and said central portion then bending inwardly in the upper part of the band whereby said tooth engaging surface is curved to define a concave configuration, said lower part exTending angularly upwardly and outwardly from the lower edge of the band for about two-thirds of the height of the central portion, and said upper part bending upwardly and inwardly in the upper one-third of the central portion.
 2. A construction in accordance with claim 1 wherein said band is bent along a vertical axis extending through said central portion with said arms extending on opposite sides of a vertical plane extending through said axis, the concave tooth-engaging surface comprising the interior surface of the band.
 3. A construction in accordance with claim 2 wherein said concave configuration extends from the juncture of one arm with said central portion throughout the entire extent of the central portion to the juncture with the other arm.
 4. A construction in accordance with claim 3 wherein said arms define a bottom edge formed as an extension of the bottom edge of said central portion, the respective bottom edges combining to form a substantially straight bottom edge, said bottom edge being positioned adjacent the gingival border when the band is in position on a tooth.
 5. A construction in accordance with claim 3 wherein the upper edge of said central portion curves upwardly from one of said junctures to a mid-point of the central portion and then curves downwardly to the other of said junctures whereby said central portion is progressively wider from said junctures to the mid-point of the band. 